New York » The U.S. is losing the battle of the bulge, and Mississippi is the state reporting the largest percentage of fat people.

The number of states with an adult obesity rate of 30 percent or more has tripled, to nine, since 2007, the U.S. Centers for Disease Control and Prevention said in a report yesterday. Mississippi had the highest rate, 34 percent. About 75 million Americans are considered obese, the Atlanta-based CDC said.

Being fat is costing Americans as much as $150 billion a year from ills such as diabetes, heart disease and cancer, as obese people carry almost $1,500 more in yearly medical expenses, the CDC said in the report. The Obama administration and public-health officials have made fighting flab a priority, organizing campaigns to get people to eat less, consume more fruits and vegetables, and get more physical activity.

"This is a call to action for the nation," said Heidi Blanck, the CDC’s branch chief for obesity prevention and control. "It took over a decade for smoking prevention efforts to take effect. We’re still in our infancy on diet and exercise."

Besides Mississippi, the states with 30 percent or higher obesity are Alabama, Arkansas, Kentucky, Louisiana, Missouri, Oklahoma, Tennessee and West Virginia, the CDC said. Thirty-nine states showed increases in their rates. In 2000 no state had a rate of 30 percent or more, according to the public health agency.

The majority of states, including Hawaii, had obesity rates of between 20 percent and 29 percent. Only Colorado and the District of Columbia had obesity rates of less than 20 percent.

Colorado’s relative thinness might relate to the fact that two-thirds of the population lives in the mile-high city of Denver. The high altitude, which requires more exertion from people, is keeping weight off, said William Dietz, director of the CDC’s division of nutrition, physical activity and obesity. Colorado also has a "culture of physical activity," he said.

"The District of Columbia is more of a mystery," Dietz said. "It may have to do with the city’s higher rates of breast-feeding and consumption of fruits and vegetables."

To determine whether someone is obese, researchers calculate the BMI, or body mass index, which is weight divided by the square of height. "Normal" index numbers are 18.5 to 24.9. Doctors deem patients to be "overweight" at an index figure of 25 to 29.9, and "obese" at 30 or higher.

A 5-foot-5-inch woman is considered overweight at 150 pounds and obese at 180. A 6-foot man is overweight at 184 pounds and obese at 221.

"Obesity continues to be a major public health problem," CDC Director Thomas Frieden said in a statement yesterday. "We need intensive, comprehensive and ongoing efforts to address obesity. If we don’t, more people will get sick and die from obesity-related conditions such as heart disease, stroke, type 2 diabetes and certain types of cancer, some of the leading causes of death."

States and the federal government have been creating programs to influence people’s food choices, including removing sweet beverages such as soda and fruit drinks from schools. New York City has required chain restaurants to list calorie counts for meals.

The Food and Drug Administration is working on a national standard for listing calories in chain restaurants, based on a requirement set in the health care overhaul passed in March, Blanck said. Those rules might be issued next year, she said.

The CDC report is based on Behavioral Risk Factor Surveillance, which collects state public health data. The statistics on obesity are collected through phone surveys and are likely to produce underestimates since both men and women tend to overestimate their height and underestimate their weight, according to the CDC.

CORRECTION: Body mass index comprises a person’s weight in kilograms divided by the square of the person’s height in meters. An inaccurate oversimplification of this formula was given in a previous version of this article on obesity.